Resummed Cross Section for Jet Production at Hadron Colliders

We study the resummation of large logarithmic perturbative corrections to the single-inclusive jet cross section at hadron colliders. The corrections we address arise near the threshold for the partonic reaction, when the incoming partons have just enough energy to produce the high-transverse-momentum final state. The structure of the resulting logarithmic corrections is known to depend crucially on the treatment of the invariant mass of the produced jet at threshold. We allow the jet to have a non-vanishing mass at threshold, which most closely corresponds to the situation in experiment. Matching our results to available semi-analytical next-to-leading-order calculations, we derive resummed results valid to next-to-leading logarithmic accuracy. We present numerical results for the resummation effects at Tevatron and RHIC energies.Comment: 10 figures include

Socio-Technical Phenomena Involving Blockchains: Review, Critique and Agenda

The paper reviews and assesses the state of blockchain research and conceptualises blockchain uses as socio-technical phenomena. The first blockchain use case emerged with the release of Bitcoin in 2008. Since then, blockchain use has proliferated in various other areas and encompassed an array of applications, such as tokens (cryptocurrencies and non-fungible tokens), decentralised autonomous organisations and smart contracts. The paper presents a structured literature review of 113 research papers in information systems and related fields (e.g., organization studies, management and human- computer interaction) that commonly study socio-technical phenomena and organisational uses of technology. Conceptualising blockchain uses as socio-technical phenomena highlights the necessity to account for business models, social implications and stakeholders’ values regarding blockchains beyond the blockchain technology ‘as such’. The review reveals that the existing literature has articulated substantial knowledge of some aspects of blockchain uses but lacks knowledge in other aspects. Therefore, we propose a research agenda

Determining The Capacity Requirements Of Coal Mine Gathering Belts.

In coal mining the belt haulage system can be resolved into three component belt types: section belts, transfer belts, and gathering belts. In contrast to section and transfer belts which receive loads from a single source, gathering belts receive loads from two or more sources. Therefore the capacity requirements for these belts are dependent upon the individual source loads that will superimpose on them. Since belt loading is intermittent and often of short and varying duration, it is difficult to determine the extent of this superimposing. Consequently, the capacity requirements of gathering belts can not be exactly calculated, but they can be predicted by either empirical formulas or computer simulation models. While simulation models are considered to be accurate, their application is often very time consuming and burdensome. Hence, in the preliminary stages of mine design and also when decisions must be made quickly, reliable empirical methods are often preferred. In order to establish their reliability, an evaluation of the empirical methods for designing gathering belt capacity was undertaken in this study. The first step in this evaluation consisted of identifying the existing empirical methods. Only two were found: the safety factor method and the peak capacity method. Since it was not possible to apply the empirical designs to operating belt systems and then evaluate their effects directly, a computer simulation model was needed for this purpose. Although several simulation models are available, all of them contain deficiencies. Therefore, a substantial portion of this study involved developing a new model which would overcome many of these deficiencies. When this new model is applied, a more realistic and accurate belt capacity simulation can be achieved. Once the new model was developed and field loading data was collected, simulations were made to evaluate numerous empirical designs that were applied to hypothetical belt systems. These evaluations lead to recommendations for applying the peak capacity and safety factor methods, a new empirical method, and recommendations for further study. If the recommendations and the new empirical method are applied, reliable empirical design can be achieved

Fractional total colourings of graphs of high girth

Reed conjectured that for every epsilon>0 and Delta there exists g such that the fractional total chromatic number of a graph with maximum degree Delta and girth at least g is at most Delta+1+epsilon. We prove the conjecture for Delta=3 and for even Delta>=4 in the following stronger form: For each of these values of Delta, there exists g such that the fractional total chromatic number of any graph with maximum degree Delta and girth at least g is equal to Delta+1

Optical and near-IR spectroscopy of candidate red galaxies in two z~2.5 proto-clusters

We present a spectroscopic campaign to follow-up red colour-selected candidate massive galaxies in two high redshift proto-clusters surrounding radio galaxies. We observed a total of 57 galaxies in the field of MRC0943-242 (z=2.93) and 33 in the field of PKS1138-262 (z=2.16) with a mix of optical and near-infrared multi-object spectroscopy. We confirm two red galaxies in the field of PKS1138-262 at the redshift of the radio galaxy. Based on an analysis of their spectral energy distributions, and their derived star formation rates from the H-alpha and 24um flux, one object belongs to the class of dust-obscured star-forming red galaxies, while the other is evolved with little ongoing star formation. This result represents the first red and mainly passively evolving galaxy to be confirmed as companion galaxies in a z>2 proto-cluster. Both red galaxies in PKS1138-262 are massive, of the order of 4-6x10^11 M_Sol. They lie along a Colour-Magnitude relation which implies that they formed the bulk of their stellar population around z=4. In the MRC0943-242 field we find no red galaxies at the redshift of the radio galaxy but we do confirm the effectiveness of our JHK_s selection of galaxies at 2.3<z<3.1, finding that 10 out of 18 (56%) of JHK_s-selected galaxies whose redshifts could be measured fall within this redshift range. We also serendipitously identify an interesting foreground structure of 6 galaxies at z=2.6 in the field of MRC0943-242. This may be a proto-cluster itself, but complicates any interpretation of the red sequence build-up in MRC0943-242 until more redshifts can be measured.Comment: 17 pages, 14 figures, accepted for publication in Astronomy and Astrophysic

Optimization of a sea ice model using basinwide observations of Arctic sea ice thickness, extent, and velocity

A stand-alone sea ice model is tuned and validated using satellite-derived, basinwide observations of sea ice thickness, extent, and velocity from the years 1993 to 2001. This is the first time that basin-scale measurements of sea ice thickness have been used for this purpose. The model is based on the CICE sea ice model code developed at the Los Alamos National Laboratory, with some minor modifications, and forcing consists of 40-yr ECMWF Re-Analysis (ERA-40) and Polar Exchange at the Sea Surface (POLES) data. Three parameters are varied in the tuning process: Ca, the air–ice drag coefficient; P*, the ice strength parameter; and α, the broadband albedo of cold bare ice, with the aim being to determine the subset of this three-dimensional parameter space that gives the best simultaneous agreement with observations with this forcing set. It is found that observations of sea ice extent and velocity alone are not sufficient to unambiguously tune the model, and that sea ice thickness measurements are necessary to locate a unique subset of parameter space in which simultaneous agreement is achieved with all three observational datasets